Because they too have been from one side of this galaxy to the other and seen alot of strange stuff, but they have never seen anything to make them believe that there is one All Powerful Force controlling everything.

"You're right, it is disturbing - never knowing when that impulse may come, or whether or not you can control it when it does. You live on the edge of every moment. And yet, in its own way, violence is attractive too. Maybe because it doesn't require logic. Perhaps that's why it is so liberating."
- Star Trek Crewman Lon Suder